I'm assuming that you installed the original files in the first place.
If you dragged the update files into the BD directory and answered "yes" to the "do you want to overwrite" then it would have overwritten them just fine.
Which OS are you using? There are, for example, some particulars that must be observed with Vista that don't matter for XP, so we'd need to know that before we could give you any sort of suggestions of things to try.
